Looking for opinions…for a cast iron structural component (steering knuckle) with ~50k miles, is this an unusual amount of rust? In my experience, I would say yes, but looking for an objective second opinion. 2nd question—would you replace it for safety reasons or is there likely enough material there that it will be fine?
thanks!

 

What year is your RDX?

In my novice opinion, the knuckle is rusting much faster than the surrounding parts. If it were me, I would ask my mechanic about replacing it the next time I got it serviced.

 

Ditto on the model year. I'd definitely get it replaced asap. That thing looks extremely rusted out...

 

Thanks—it’s a 2016. Yea, I’m planning to replace them.

 

Spray the new ones with some Fluid FIlm!

 

Great suggestion! I got some used knuckles that have only minor (normal) surface rust. I’ll get some fluid film to spray on those, thanks!

 

Cast steel. That amount of rust scaling is insignificant. Rust scale is at least four times the thickness as the steel that corroded to create it.

It will outlive the rest of the car.